This invention relates to retarding the decomposition of hydrogen peroxide in aqueous solution.
Dilute aqueous hydrogen peroxide in concentrations of between about 3 and 10 weight percent has many uses, including bleaching, hair dyeing and waving, processing of photographs for permanence, and preparation of cosmetics and mild antiseptics.
Hydrogen peroxide is commonly sold in concentrated aqueous solutions of between about 30 and 90 weight percent, which are often diluted by the purchaser for use or sale. The concentrated solutions are quite stable when pure, but contaminants which promote decomposition may be introduced in storage and handling. The common use of tap water for dilution of the concentrate may introduce significant quantities of decomposition-inducing cations such as iron, copper, and manganese cations. If diluted solutions are stored rather than used immediately, substantial decomposition may occur.
Numerous organic and inorganic stabilizers for aqueous hydrogen peroxide are known. Various combinations of stannate, nitrate, orthophosphate, and pyrophosphate ions for use at varying pH have been proposed. See, for example, U.S. Pat. Nos. 3,701,825, 3,373,113, 3,591,341, and 3,607,053. U.S. Pat. No. 3,781,409 discloses the use of water-soluble tin compounds, preferably in conjunction with organic complexing agents such as organic phosphonic acids, 8-hydroxyquinoline, hydroquinone, nitrilo triacetic acid, alkyl phenols, and phosphate esters. U.S. Pat. No. 3,681,022 discloses the use of nitrilo trimethylene phosphonic acid and alkali metal stannate.
It has now been found that decomposition of aqueous hydrogen peroxide solutions may be retarded by dissolving therein a minor stabilizing concentration of a 3-N-morpholinylpropionitrile, which may be used alone or, preferably, in combination with known stabilizing additives, notably stannates, or more preferably, in combination with stannates, nitrates, and pyrophosphates.